Vari-drive belt replacement on KM3P

[shaynut]

The belt on my KM3P is shot and needs to be replaced. I found some instructions on the hurco.com site but was wondering if anyone had any "tips or hints" to the documented procedure that might save me from making a mistake. I have a hand-held tach to use to recalibrate the speed control when I get to that point. The instructions aren't really clear on just which castings need to be removed. Also, I'm not sure what the instructions mean when it says to "float in the spindle motor while adjusting all the mounting bolts".

[shaynut]

Update: I got it all torn apart last night but it wasn't nearly as easy or straight-forward as I thought it might be. The biggest issue was getting the main casting over the brake shaft. It was very awkward to say the least.

Now I have a couple of new questions....
1) The nylon bushings that ride on the splined shafts (front and on the motor shaft) seem pretty worn to me. Neither splined shaft had any lubrication left on it. How can I tell if the nylon bushings are worn out and need to be replaced? There seems to be considerable "wobble" in both of them. I measured the total wobble on the front bushing and got 5/32" total deflection between the upper and lower belt pulley plates measured at the outer rim of the pulley plates.

2) The upper pulley plate on the front shaft has a casting mounted to it that the yoke that is used to control the vari-drive is bolted onto. This casting appears to have an internal bearing. In my case, this bearing is extremely dry sounding. Is this a bearing that should be replaced or can I just oil it a bit and leave it?

3) I'm still looking for an explanation of how to "float in" the motor when I reassemble this mess as well as any other tips that may assist in the reassembly.

Thanks!

 

[buddy]

Yes, you need to replace both Nylon Bushings and the 3 Radial bearings as well as the Belt each time you rebuild the top head. You should get aboaut 5 years depending on your use. Take care not to run the Spindle at its extremes( Full or Min speed). I plan on writing up a proceedure soon and maybe a video. But for now you can call me and I will give you all the tricks over the phone.

Thx
Buddy Maughon
770-995-0461

[shaynut]

Thanks for info Buddy. I sent you an email with some more information based on our phone conversation. Let me know what you think.

[shaynut]

I ordered the three bearings I need for the top end rebuild using the internet today. I paid $4.95 for the top-most bearing that Hurco wants $223.00 for and I paid $9.95 each for the other two that Hurco wants $144.00 each for. I wish I could sell things with 4,505% and 1,447.2% markups respectively. I suspect I will not be so lucky when it comes to the nylon bushings that I need 

[shaynut]

BTW: the bearing numbers/sizes are:

Top-most:  35mm (id) x 62mm (od) x 14mm,  trade number: 6007-2RS double sealed, Hurco #211 0003 001 

Other two: 50mm (id) x 80mm (od) x 16mm, trade number: 6010  double-sealed  Hurco#211 0003 004   

Nylon Bushings (need two):  Hurco #713 0016 058  Quoted price: $254.25 each

[shaynut]

To make this post complete, I thought I'd post the final news on this project. As I mentioned I got the replacement bearings cheaply but I was not so lucky with the delron (not nylon as previously stated) bushings. They were anything but cheap. I ended up getting them from Hurco as I was running out of time looking for something else. As it turns out, the delron bushings come oversized and require manual fitting to its respective shaft. That was a major PITA! The bushing's O.D. was fine for slipping snugly into the sheave itself. But filing and sanding and polishing the inside splines so it fit snugly but slid easily up and down the shaft was not so pleasant a thing. It took a couple of hours (I didn't want to mess it up and have to buy another bushing!) but I got them to fit like I wanted. After that was done it only took another 30 minutes to put everything back together. After a couple of adjustments using my handheld tachometer to get the spindle speed corrected it was all done. In the end, it was worth every minute and every dollar to do the overhaul. Compared to how it operated before the overhaull, the vari-drive system is virtually silent now. It runs really smooth and doesn't rattle and growl at me like it did. I couldn't be happier! Now its time to make some chips!